The mariadb_get_infov documentation doesn't make it version clear what should be a pointer and what should be a pointer to a pointer.

https://mariadb.com/kb/en/mariadb_get_infov/

For example:
"MARIADB_CONNECTION_SCHEMA: Retrieves the current schema.
Parameter type: const char*. "

This you would use:

const char *db = NULL;

mariadb_get_infov(maria, MARIADB_CONNECTION_SCHEMA, &db);

This makes it a const char **, but:

"MARIADB_CONNECTION_MARIADB_CHARSET_INFO: Retrieves character set information for given connection.
Parameter type: const MY_CHARSET_INFO *. "

For this you would do:

MY_CHARSET_INFO charset;

mariadb_get_infov(maria, MARIADB_CONNECTION_MARIADB_CHARSET_INFO, &charset);

This makes it a MY_CHARSET_INFO*.

I think for consistency the const char* ones should say const char**.

In addition one of the examples on that page is missing a brace for void.